Hitherto, herbicidal activity of tetrahydrophthalamic acid derivatives is well known. For example, N-(4'-chlorophenyl)-3,4,5,6-tetrahydrophthalamic acid methyl ester is known, as is disclosed in JP-A (Patent) 48-44425.
However, the conventional tetrahydrophthalamic acid derivatives are not necessarily sufficient in herbicidal activity, or are substantially limited in herbicidal spectrum against weeds. Furthermore, these derivatives are insufficient in selectivity between crops and weeds, thereby inducing problems of safety for crops.
It is an object of the present invention to solve the aforementioned problems, and to provide a novel compounds which are excellent in herbicidal activity but not harmful to crops, methods of producing the same, and herbicides containing the same as the effective components.